Nitrogen physisorption on modified silica surfaces

The surface of a silica sample (Spherosil) have been modified by means of c hemical treatments with sulfuric, phosphoric, and hydrochloric acids and po tassium chloride. A sample also has been heated in a furnace at high temper atures. Changes in the degree of hydroxylation have been qualitatively foll owed by means of IR spectroscopy. Nitrogen, argon, and oxygen physisorption has been employed to study the behavior of the original and treated sample s. Monte Carlo computer simulations results have been developed to explain nitrogen adsorption isotherms obtained with the different samples.